The present invention is directed to power distribution control apparatuses. The invention is especially directed to power distribution control apparatuses in battery backed-up host systems that automatically provide power from a normal power source, such as house current, or from a battery unit depending on circumstances sensed by the apparatus itself.
A common configuration employed in battery backed-up systems is to use high voltage stepped down to charge a low voltage battery when the high voltage is present. When the high voltage is removed, the battery voltage is then stepped up by a step-up converter to provide power to the host system. In prior art configurations of such systems, two separate converters are used: a step-down converter to use the high voltage for providing a charging voltage, and a step-up converter to step up the battery voltage to a level appropriate for powering the host system. Using two converters contributes to requiring larger die space, higher part count, greater complexity and consequent possible greater opportunity for breakdown than would be experienced if a simpler configuration were employed.
There is a need for an apparatus and method for effecting power distribution to a host system from a voltage source or a battery that requires smaller die space and lower part count than are required for prior art power distribution control apparatuses.